Page numbers is also helpful when reading articles from compendiums and similar.

That is exactly the point. Page numbers are not absolute and they are completely useless in this specific situation. If you have a compendium and read it with font type Times Roman, size 11 an artikel can start on pag 234. You'll have to memorize this number if you want to go back to it. If I read the same book with Verdana size 10 I can find the same artikel on page 187. And if you still remember after a few days the artikel is on page 234, it won't be there if you were reading another book in between under different licht conditions and changed the font size/type. And it is even worse because no MobiReader version in the world is capable to find the exact spot again if you go forwards and backwards. Even if you use fixed fonts and fixed sizes.

What you need in this situation is a good Table of Content. That works the same a hyperlink. You don't care what ip address it is pointing to, but click on it and it will bring you there.

Not fake page numbers that have absolutely no relation with a precise spot in the contents of a book.